Device for hydraulic apparatuses comprising a double acting piston motor



Aprll 7, 1964 v. N. c. DUNER 3,127,817

DEVICE FOR HYDRAULIC APPARATUSES COMPRISING A DOUBLE ACTING PISTON MOTOR Filed Jan. 29, 1962 a I -7 L J 12 FIG.3

United States Patent DEVICE FOR HYDRAULIC APPARATUSES COM- PRI1NG A DOUBLE ACTING PISTON MOTOR Viking Nils Christoifer Dunr, Goteborg, Sweden, assignor to Aktiehoiaget Gotaverken, Goteborg, Sweden, a corporation of Sweden Filed Jan. 29, 1962, Ser. No. 169,532 (Ilaims priority, application Sweden Jan. 30, 1961 1 Claim. (Cl. 91-216) In hydraulic apparatuses air bubbles often cause great troubles in the system. In hydraulic double acting piston motors intended to operate heavy units and where often a long time elapses between consecutive operations, the air which may be accumulated in the power cylinder, can jeopardize the proper action. This can be the case for instance with hydraulically operated ships hatch covers. These often comprise units divided into sections, and a hydraulic piston motor may be arranged between one or some of the pairs of sections, or between a section and the coaming. By the aid of this motor the sections are moved from closed to open position and vice versa. The working cylinder of the motor will thereby be so positioned that a venting in certain cases can be ditlicult. The hydraulic double acting piston motor over which the present invention is an improvement is described and illustrated in US. Patent No. 3,056,386 which issued October 2, 1962, in the names of R. O. Aarvold et al, and assigned to applicants assignees, Aktiebolaget Gotaverken.

The present invention relates to a device for hydraulic apparatuses of the kind referred to and comprises a double acting piston motor, which during operation performs such a movement that the pressure medium conduit connection pieces during a part of the movement will be positioned lower than the highest point of the pertaining power cylinder, and the invention is mainly characterized in an overflow valve attached to the cylinder and having a valve body actuated by a spring, the pressure medium conduits being connected with said valve in such a manner that one of the connection pieces which during the working stroke of the pertaining cylinder is moved from a lower to a higher point, is connected in front of the valve body while the other connection piece, which is moved from a higher to a lower point, is connected behind said valve.

In order to make the invention clear one embodiment of the same will now be described with reference to the annexed drawing in which- FIGURE 1 is a view showing a hatch cover comprising two sections, hingedly connected to each other, one of which is provided with wheels running on tracks along the coaming and the hatch assembly has a piston motor, valves as well as a pumpand conduit arrangement,

FIGURE 2 schematically shows a device in accordance with the invention as applied to a double acting hydraulic piston motor and FIGURE 3 is a side view of the piston motor showing the alternate end positions of the connection pieces.

In FIGURES 1 and 2 numeral 1 denotes a tank for a pressure medium, 2 is a pump and 3 a manually actuated main regulating member. The system includes a twoway valve designated by 4 and an overflow valve 6. From the two-way valve 4 pressure medium can be led through a conduit 5, and passes a passage 7 in the valve 6, which in its turn communicates with a double acting piston motor by way of a conduit 8. The overflow valve 6 is arranged nearest to the piston motor, preferably attached to the same. In the valve 6 there is furthermore a through flow passage 9, which by way of conduits 10 and 11 is connected to the two-way valve and 3,127,817 Patented Apr. 7, 1964 the piston motor, respectively. The passage 9 can also be connected to the passage 7 by a boring 12. This connection is normally closed by means of a valve body 14 actuated by a spring 13. Between the two-way valve 4 and the tank 1 there is a return conduit 15. The double acting piston motor comprises a power cylinder 16 and a cylinder extension 17. At the cylinder there are connection pieces 18 and 19 adapted to receive the pressure medium supply conduits 8 and 11, respectively, and to bring the connection to the power cylinder 16 at each side of the end positions of opposed pistons 21, 21. The units intended to be actuated by a turning motion are attached to the cylinder extension 17 of the piston motor and the pin 22. The latter is a continuation of the torque bar 20 situated in and extending through the cylinder. The linear motion of the piston is transferred into a turning motion by means of co-operating helically running spline devices on the piston rod and cylindrical extension, respectively.

In the piston motor illustrated herein, a hatch opening is arranged to be closed by two hatch cover sections 32 and 33 hingedly connected to each other. Section 32 is hingedly connected to the coaming 31 of the hatch opening, and section 34 is adapted to move along the coaming on wheels 36. An operating mechanism arranged between two hinges is shown more particularly in FIG. 2. Each hinge comprises a bracket 38, preferably detachably connected to section 32, which supports a non-revolving pin 22. In a similar manner a bracket 49 is connected to section 34, and this bracket supports a non-revolving cylinder 17 which extends to the corresponding bracket of the other hinge. The pins of the two hinges, respectively, are connected by a bar 20 extending through the cylinder. This cylinder is designed to enclose the bar 21) with a certain clearance. The cylinder is provided with internal splines forming two sets of first guiding surfaces 42, while the bar 2t) is provided with two sets of helically running splines 43 forming second guiding surfaces. The cylinder 16 is provided with two pistons 21, 21 working in opposite directions under the influence of a pressure fluid. Each piston has a hollow piston rod 44 extending in axial direction with respect to the cylinder. One end portion of said hollow rod is designed as a sleeve 53 which bridges the radial clearance between the cylinder and the bar 20 and is provided with guiding means mating with the splines forming the first and the second guiding surfaces on the cylinder and on the bar, respectively. The pistons are provided with central apertures through which the bar passes, thereby providing a guide for the pistons. The cylinder is connected at 18 and 19, 19, with pressure medium supplying pipes 8 and 11, respectively, said pipes being connected to the cylinder at each side of the respective end positions of the piston. The length of the part of the bar 2t) provided with splines and the pitch of the helical splines are chosen in such a manner that the desired movement between the parts will be obtained-in this case degrees. The splines on the cylinder may also be helical in order that a greater turning movement for a smaller piston stroke be obtained.

The device in accordance with the invention will work in the following manner. When an angular displacement is desired between the two hatch cover sections as shown in FIGURE 1 from closed to open position, the valve 4 is so regulated that pressure medium by the conduit 5 passes the passage 7 in the valve 6 without actuating the same and is then led through the conduit 8 to the portion between pistons 21 in the power cylinder 16, which is served by the connection piece 18. Both connection pieces 18 and 19 are, when the movement is initiated, positioned at I in FIGURE 3, i.e., they its original position.

are directed upwards. When the pistons 21 under the influence of the pressure medium begin to move and at the same time bring about a turning motion between the parts 16, 17 and 22, respectively, the cylinder is displaced in the direction of the dashed arrow in FIG. 3

and the connection pieces will finally be positioned at II.

Possible air bubbles which since the preceeding operating occasion have liberated themselves from the oil remaining in the cylinder outside of the pistons 21, 21 have been able to escape through the connection piece 19,

which during the interval has been turned upwards.

During the outward movement of the pistons pressure medium is discharged through passage 9, conduit 10, twoway valve 4 and back flow conduit 15 back to the tank 1, and the air bubbles are thus removed from this part of the system. If an opposite movement is desired, i.e. lowering the sections to closed position, the valve 4 is switched over in such a manner that the pressure medium passes conduit 10, passage 9, connection conduit 11 to the connection piece 19 of the cylinder 16. Both pistons 21 then move inwardly. During this operation the connection pieces 18, 19 are moved from position 11 to I in FIGURE 3, as the power cylinder is turned back to The oil between pistons 21, 21 will be discharged at 18, and is by way of conduit 8, passage 7, valve 4 and conduit 15 returned to the tank 1. Such air bubbles, which are liberated in this cylinder portion can not escape until the connection piece 18 has reached its top position. At that time the discharge of oil from this cylinder portion is mainly finished which means that the bubbles will remain in the system close by the cylinder or in the valve. In connection with a following pressure stroke, in the opposite direction, they probably will be returned to the cylinder. It must be remembered, in this connection, that the condiuts 5 and in practice will be of greater length than the conduits 8 and 11 and that the bubbles of their own account only move upwards, whereas they of course will be swept along by a flow of fluid.

If the main regulating valve 3 kept open also after the piston motor has performed the inward working stroke, the valve 14 will open and pressure medium will flow back by the way of conduit 15. Possible air bubbles from the conduit 8 are thereby carried away and thus removed from this part of the system.

The valve has a further function in the system. In

the present case the hatch covers are moved to a position fixed by a stop. In such hatch covers comprising a number of hingedly connected sections, it could happen that a continued pressure medium supply causes a raising of some of the hatch covers from the coaming beyond the desired horizontal position. This requires, however, more work than the ordinary opening movement and can be prevented if the spring load on the valve is so dimensioned, that the valve opens it the motor, after having performed the movement intended is supplied with pressure medium.

What I claim is:

In a pressure fiuid medium-operated mechanism for bringing about angular displacement between a first part and a second part connected to each other by means of at least two hinges as said parts move from a first position to a second position, an actuating device consisting of a tubular part connected to the first of said parts between the hinges and a piston reciprocable in opposite directions in said tubular part under the influence of fluid pressure and connected to the second of said parts,

means for selectively introducing fluid under pressure to either side of said piston for effecting a turning movement between said tubular part and said piston said means including connections on said tubular part communicating with opposite sides of said piston and pressure fluid conduits attached to said connections,

means mounting said tubular part on one of said first and second parts which, during operation of said motor, shifts its position with respect to a horizontal plane in such manner that in one of said first and second positions said connections coincide with the highest point in the pertaining tubular part;

a passage interconnecting said pressure fluid conduits immediately adjacent said connections; and

an overflow valve in said passage arranged to open in the direction towards that pressure fluid conduit which, while acting as a return flow from the pertaining tubular part, moves from a lower to a higher position.

References Cited in the file of this patent UNITED STATES PATENTS 

